package workers

import (
	"context"
	"fmt"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"go.uber.org/zap"
	"sync"
)

type WatchWorker struct {
	accountChannels map[string][]chan map[string]interface{}
	mu              sync.Mutex
	mongoDB         *mongo.Collection
	logger          *zap.Logger
}

func NewWatchWorker(mongoDB *mongo.Collection, logger *zap.Logger) *WatchWorker {
	return &WatchWorker{
		accountChannels: make(map[string][]chan map[string]interface{}),
		mongoDB:         mongoDB,
		logger:          logger,
	}
}

func (w *WatchWorker) Run(ctx context.Context) {
	pipeline := mongo.Pipeline{
		{{"$match", bson.M{"operationType": "update"}}},
	}
	opts := options.ChangeStream()
	opts.SetFullDocument(options.UpdateLookup)
	changeStream, err := w.mongoDB.Watch(ctx, pipeline, opts)
	if err != nil {
		w.logger.Error("error start change stream", zap.Error(err))
		return
	}
	defer changeStream.Close(ctx)

	for {
		if changeStream.Next(ctx) {
			var changeEvent struct {
				FullDocument struct {
					UserID string `bson:"userId"`
				} `bson:"fullDocument"`
				UpdateDescription struct {
					UpdatedFields map[string]interface{} `bson:"updatedFields"`
				} `bson:"updateDescription"`
			}
			if err := changeStream.Decode(&changeEvent); err != nil {
				w.logger.Error("error decode change event", zap.Error(err))
				continue
			}

			w.mu.Lock()
			channels, ok := w.accountChannels[changeEvent.FullDocument.UserID]
			w.mu.Unlock()
			if !ok {
				fmt.Println("userID", changeEvent.FullDocument.UserID)
				fmt.Println("fields", changeEvent.UpdateDescription.UpdatedFields)
			}
			if ok {
				for _, ch := range channels {
					select {
					case ch <- changeEvent.UpdateDescription.UpdatedFields:
					case <-ctx.Done():
						return
					}
				}
			}
		}

		select {
		case <-ctx.Done():
			return
		default:
			fmt.Println("default select case")
		}
	}
}

func (w *WatchWorker) AddChannel(userID string, ch chan map[string]interface{}) {
	w.mu.Lock()
	defer w.mu.Unlock()
	w.accountChannels[userID] = append(w.accountChannels[userID], ch)
}

// todo подумать как дропать если с одного устройства могут выйти на другом нет а ключ с массивом один
func (w *WatchWorker) DropChannel(userID string) {
	w.mu.Lock()
	defer w.mu.Unlock()
	fmt.Println("drop chan, userID:", userID)
	delete(w.accountChannels, userID)
}